Original environment rehabilitation manual 3.363

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By this point, most project organizers will have an idea of the general area where they want the rehabilitation to occur, but many not know exactly where to do it. In this case, you must identify sites within the target area (the area of the damaged reef) to conduct detailed bottom surveys that help narrow down the exact locations on where to place the modules.

Determining which sites to survey[edit | edit source]

Determining which sites to survey is a process of elimination. The best place to start is a mariner’s chart with depths (A free US chart source is http://www.navquest.com). It’s very useful to supplement chart information with additional information sources like Google Earth™, a free web based application that provides satellite images of various detail anywhere on earth. There are often government or privately available Geographical Information Systems (GIS) databases that can be helpful in getting system detail. Libraries, web searches and local contacts can aid in revealing data or studies that have been done in the proposed area. It is useful to know currents, wave heights, tide ranges, etc. These can be sometimes be found in formal scientific literature, but it is often a good idea to get the input of local people that spend time on or in the water, such as fishermen, boat captains, and SCUBA divers because these types of conditions can be quite variable, seasonal, or site specific. Find out about water clarity, local pollution, traditional fishing areas, the effect your modules will have on the fish/ecosystem in that area (eg will it lure the some fish away, therefore attract other predators, ...) and discuss other aspects of your project to maximize your information gathering. Once you have gathered as much information as possible from these, and any other sources of data you may know, begin eliminating areas that are not suitable for your project. It may be helpful to photocopy your map, or use a computer program and physically block out areas that are not suitable.

In order to focus your thinking, below, you will also find a additional list from the US EPA of some additional areas to exclude when precising the location of your modules:

  • There are coral predators or coral diseases present at certain parts of the damaged location that will thwart rehabilitation efforts
  • The damaged location is unacceptably vulnerable to future damage
  • We don't have the skill or resources to work within the area without the possibility of doing further damage to the healthy portions of the reef.
  • We don't have the skill or resources to work with the depth range of the damaged reef
  • Shipping lanes
  • Restricted military areas
  • Areas of poor water quality (e.g., low dissolved oxygen, dredged material disposal sites, Sewer outfalls, river drainage, and other point sources of pollution)
  • Traditional trawling grounds
  • Unstable bottoms
  • Areas with extreme currents, or high wave energy
  • Existing right-of-ways (e.g., oil and gas pipelines and telecommunication cables)
  • Sites for purposes that are incompatible with reef development

Most marginal areas should also be eliminated from consideration. Do not overlook local restrictions as well. For example, building inside locally designated marine reserves usually requires special permits, which may be difficult or impossible to obtain. Do the necessary research to ensure that you know the permitting regulations for your chosen sites to avoid unpleasant surprises later on. Often, marking out areas too shallow or too deep for your project can eliminate a large portion of the otherwise suitable areas. Consider any constraints that may be imposed by your project goals. Talk with your team and add constraints they suggest. It is also best to avoid areas with healthy reefs, sea grass beds, or other live bottom types unless you have very specific goals in mind.

Now that all of the unsuitable places have been eliminated, reverse the procedure. From the areas left over, where is it best to build? Do your goals or does your team suggest an ideal depth? From a substrate point of view, keep in mind that the easiest place to add artificial reef substrate is an empty sandy bottom that has hard rock or firm bottom 10-20 cm below. Firm sand is okay. Hard bottom is fine if it does not contain a fouling community. Your team and goals may provide ideas for ideal sites, for example where currents will carry the larval coral and fish generated by your rehabilitation efforts to places where they are needed. Go back to those goals one more time…what do they suggest to you about where to build? If you are doing an erosion control project, you may have very tight tolerances for potential sites in this case you will need the assistance of a coastal engineer. By the end of this process, you should have identified at least one and often several areas that fit your project criteria. It will be easiest if you identify these locations using GPS coordinates (specify map datum).

Bottom Survey[edit | edit source]

At this point, you have one or more sites selected and you need to determine if the site is suitable for deploying a base substrate and supporting coral. This survey is best conducted by SCUBA/SNUBA/surface supplied diving but it is possible to snorkel for shallow areas.

In addition to your SCUBA/snorkeling gear, you will need the following equipment:

depth Gauge & Compass
measuring reel
Various styles of site marking buoys (SCUBApro left, generic middle, and Cressi-sub right)
Underwater slate
  • Depth Gauge & Compass (even if snorkeling, but wrist mounted is preferred for snorkelers)
  • Small hand-held sledge hammer
  • (2 or more )1 meter lengths of #5 rebar (5/8’ or 1.59 cm) diameter iron rebar (If possible, mark the rebar stakes so you can use it as a measuring tape)
  • Fiberglass tape measuring reel of more than 50 meters (Don’t use metal tapes, they will rust)
  • GPS-receiver (hand-held or boat-mounted)
  • Digital Camera and Underwater Case (Always clean and lubricate o-ring before use. Pack & seal in a low humidity environment, such as an air conditioned room, before diving. If you must transport the camera for any duration in hot conditions after packing keeping it in a small bucket or plastic bag full of water will help avoid sudden temperature changes and damage. When possible use a larger memory stick and fully charged battery so you do not have to open the camera in the field.) Note: RBF Coral Team uses Cannon Powershot (400-700 series) with manufacturer’s underwater case which is economical and allows white balance function while working underwater which is essential for true color photographs). Most any underwater setup is suitable for this step but compactness is helpful due to other tools being carried.
  • Underwater slate, strap, graphite pencil & eraser. Note: Solid graphite pencils (available at art stores) are more reliable in marine use. (AquaSketch [1] makes advanced specialty slates especially well suited for survey and scientific work.)
  • Site Marking Buoys: 4 or more marking buoys (many different types will work, even a milk jug tied to a dive weight). Whatever style you select, make SURE it is stable enough for the wave conditions and has enough line for the depth so that it does not move. Marking buoys made especially for divers with enclosed weight such as the SCUBApro buoy signal (shown below) are easiest to use.

Once you have your equipment ready, and when diving/boating conditions are good follow this procedure. Go to the site and anchor up so that your boat is in the center location of the area you want to survey. When the anchor is well set, throw in a marker buoy and take a GPS reading. Dive to the bottom below the boat and start at the marker buoy (which should be the same place as your GPS reading). Record the depth and look to see if the site contains enough open space to place your base structures. If it is obvious right away that the site is not suitable, for whatever reason, proceed immediately to the next site. Don’t waste the day surveying sites that you probably won’t use. If it looks good, ideally open sandy areas with hard bottom below and otherwise clear, then continue. If it is hard bottom, use the camera to record that there is no growth or fouling community on the hard bottom. If sand, take your rebar and carefully drive it into the bottom making even strokes counting them as you drive the stake. Your stroke should allow the hammer to fall under it’s own weight, guided by a little added pressure for guidance from a distance of about 0,3 m (1 foot). Record the depth to firm bottom and the number of strokes it takes to get there. If you do not hit firm bottom, record the number of strokes to go 0,6m deep (2 feet). It is important to be consistent with this process between sites so you can compare the relative softness of the different sites. This will help you determine when there is no hard bottom below the sand and if it is firm enough to support your chosen base substrate or artificial reef. Note: Contact the supplier of your base substrate or artificial reef designer to determine how firm the bottom sand must be to avoid subsidence for your selected material if firm bottom is not found within 0-20 cm of the bottom surface. Do not plant coral closer to the seafloor than the distance to hard bottom determined by this survey on any material that is not supported by anti- subsidence anchoring or the coral may eventually be covered by sand, you may need an even larger safety distance to account for possible accretion. There are advanced anchoring options for difficult situations but this will require further investigation not covered by this manual. Use your slate to start drawing a map with your current location being the center point. Leave this first rebar stake in the sea floor and lay your tape measure over the rebar. Decide roughly how big of an area you want to survey. Then extend your tape out to that length heading in a compass direction of due east (or whichever point on the compass (N, S, E, or W) is most perpendicular to the current, to preserve your visibility). Then, take your next sample by repeating the rebar procedure or taking a photo of the hard bottom and then place one of your marking buoys at this place. Mark your slate with the information and then do the remaining points (either rebar or photographic method depending on bottom type). As you sweep around directions, use the tape measure to determine distance from the center and map any areas that are not suitable for deployment (such as on an existing reef head, or were the bottom appears too soft). Take notes on anything you find unusual that could affect your project such as changes in depth. Take digital photos of the general area and any specific features as you go. Finally, return to the center reeling in your tape as you go and retrieve your first rebar. When you surface, remove the anchor and travel to each buoy location and take GPS readings and retrieve your buoys. Record which map datum your GPS is using, especially if you may use a different GPS for deployment day. If you have a secchi disk, it is nice, but not required to record the water visibility. This helps when interpreting the accuracy of the findings. Secchi disk readings must be repeated over time if you want to have an ideal of the average visibility. Time permitting, a secchi disk can be made by attaching a marked line to any roughly circular flat white object (such as a plastic bucket lid) and blacking out 2 of the 4 quadrants with black permanent marker or electrical tape. A quick Internet search will yield several guides to building a homemade version, for example, http://web.archive.org/web/20150226203540/http://angfa.org.au/secchi.html.

Hopefully, this process will help you to identify the ideal site or sites. When you have finished surveying, transfer all of your data from the slate and digital camera into a computer and organize it while it is fresh in your mind. Everyone has their own methods for organization of the data. We have found Google™’s free program Sketch-up to be very useful for making 3-D drawings of the actual and planned site. These can be geo-referenced to Google Earth™ but if you do this you can’t see negative elevations. We have already created a large library of 3-D models that can be imported into Sketchup for your use including scale models of all sizes of Reef Balls.

Helpful Tip: Many of the 3-D renderings of objects you will see in this manual were made with Sketchup™ and are available on-line. Go to the glossary under Coral Propagation Table for instructions to get Sketch-up and the models. Use other keywords like ‘Reef Ball’ to find even more models.

Sometimes it takes a while to find a suitable site; sometimes you get lucky and find it on the first dive. Occasionally, there is no suitable place and if that is the case you need to consider an alternate location, or another rehabilitation option. If possible, it is always best to find a few backup sites in case the situation changes, and water quality or another variable makes your chosen site less desirable.

Validate Site Water Quality Supports Goals[edit | edit source]

Now you have a selected a site that is physically suitable, and that is desirable from a goal stand point of view. The next thing is to do is to make sure the water quality is suitable for your rehabilitation goals. If the water quality is not suitable you must either fix the problems affecting the water or go back to the bottom survey and try again. Fixing water quality is not usually within the scope of smaller grassroots projects, however, it is always desirable to improve water quality whenever practical. Perhaps there are point sources of pollution that can be identified and controlled. Perhaps a reef clean-up after a damaging storm is in order. Use common sense to implement these changes if you can. For now, let’s assume you have done what you can for your selected site and need to determine if the water quality is now suitable enough for your project.

Next, look at your goals and determine the most environmentally sensitive specie(s) that you are trying to protect or rehabilitate. Generally, most projects fall into one or more of these broad classes that share similar water quality requirements:

  • Fish
  • Soft coral and hardy hard coral, or non-coral reef builders (such as oysters, mussels, etc.
  • Fish with tropical hard coral
  • Tropical hard coral only
  • Any of Above plus specific target species (such as lobster, or particular fish species, etc).

Once you have identified which category your project falls within, read all of the categories below which pertain to your project.

To determine whether the water purity, salinity and dissolved oxygen fall within the range, see ?, Original environment rehabilitation manual 3.1 and, Original_environment_rehabilitation_manual_3.2

Site specifics negatively influencing human use goals[edit | edit source]

For example, if you are trying to create a site for SCUBA or snorkeling activities be sure the site is safe from currents or other human perils and the visibility is sufficient for underwater recreational activities. If you are creating a site for artisanal fisheries, make sure the sites are convenient and productive enough for their needs. The site selection, in this case, can literally be a matter of life and death. Thousands of fisher people die each year going too far out to fishing grounds in boats ill equipped for the task. If your team identifies conflicts go back and re-do the bottom survey otherwise proceed.

Disclaimer[edit | edit source]

This information was Reef Ball's Draftguide document.